Based on an initial implementation by Dan McArdle at
https://boringssl-review.googlesource.com/c/boringssl/+/46784
This CL contains most of a client implementation for
draft-ietf-tls-esni-10. The pieces missing so far, which will be done in
follow-up CLs are:
1. While the ClientHelloInner is padded, the server Certificate message
is not. I'll add that once we resolve the spec discussions on how to
do that. (We were originally going to use TLS record-level padding,
but that doesn't work well with QUIC.)
2. The client should check the public name is a valid DNS name before
copying it into ClientHelloOuter.server_name.
3. The ClientHelloOuter handshake flow is not yet implemented. This CL
can detect when the server selects ClientHelloOuter, but for now the
handshake immediately fails. A follow-up CL will remove that logic
and instead add the APIs and extra checks needed.
Otherwise, this should be complete, including padding and compression.
The main interesting point design-wise is that we run through
ClientHello construction multiple times. We need to construct
ClientHelloInner and ClientHelloOuter. Then each of those has slight
variants: EncodedClientHelloInner is the compressed form, and
ClientHelloOuterAAD just has the ECH extension erased to avoid a
circular dependency.
I've computed ClientHelloInner and EncodedClientHelloInner concurrently
because the compression scheme requires shifting the extensions around
to be contiguous. However, I've computed ClientHelloOuterAAD and
ClientHelloOuter by running through the logic twice. This probably can
be done better, but the next draft revises the construction anyway, so
I'm thinking I'll rework it then. (In the next draft, we use a
placeholder payload of the same length, so we can construct the
ClientHello once and fill in the payload.)
Additionally, now that we have a client available in ssl_test, this adds
a threading test to confirm that SSL_CTX_set1_ech_keys is properly
synchronized. (Confirmed that, if I drop the lock in
SSL_CTX_set1_ech_keys, TSan notices.)
Change-Id: Icaff68b595035bdcc73c468ff638e67c84239ef4
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/48004
Reviewed-by: Adam Langley <agl@google.com>
Computing the binders on ClientHelloInner is a little interesting. While
I'm in the area, tidy this up a bit. The exploded parameters may as well
be an SSL_SESSION, and hash_transcript_and_truncated_client_hello can
just get folded in.
Change-Id: I9d3a7e0ae9f391d6b9a23b51b5d7198e15569b11
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/47997
Reviewed-by: Adam Langley <agl@google.com>
We misread (or maybe it changed?) the draft padding scheme. The current
text does not round the whole payload to a multiple of 32, just the
server name as a fallback. Switch the GREASE size selection to match.
Although, we may want to change the draft here. See also
https://github.com/tlswg/draft-ietf-tls-esni/issues/433
While I'm here, update some references from draft-09 to draft-10. Also
make the comment less verbose.
Bug: 275
Change-Id: I3c9f34159890bc3b7d71f6877f34b895bc7f9b17
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/47644
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
This CL implements the backend server behavior described in Section 7.2
of draft-ietf-tls-esni-09.
Bug: 275
Change-Id: I2e162673ce564db0cb75fc9b71ef11ed15037f4b
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/43924
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
It's not even accurate. The term "master key" dates to SSL 2, which we
do not implement. (Starting SSL 3, "key" was replaced with "secret".)
The field stores, at various points, the TLS 1.2 master secret, the TLS
1.3 resumption master secret, and the TLS 1.3 resumption PSK. Simply
rename the field to 'secret', which is as descriptive of a name as we
can get at this point.
I've left SSL_SESSION_get_master_key alone for now, as it's there for
OpenSSL compatibility, as well as references to the various TLS secrets
since those refer to concepts in the spec. (When the dust settles a bit
on rfc8446bis, we can fix those.)
Change-Id: I3c1007eb7982788789cc5db851de8724c7f35baf
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/44144
Reviewed-by: Adam Langley <agl@google.com>
David Benjamin
Dan McArdle
Adam Langley